I went to Home Depot today looking for supplies to block the lower grille opening, but only found pipe insulation. I couldn't find anything else to use, so I was happy to come across the pipe insulation @ only $3 for a 6ft tube.
I basically just cut the 6 ft tube in two 3 ft pieces and nudged them in between the horizontal grille bars and pushed both ends through the last left & right openings. The foam tube ends extend maybe 6" inside the bumper but do not touch the radiator. They seem pretty well FITted in place; test-drove 10 min at high speed and they didn't move at all. Didn't use any glue, tape or zip-ties since they appear to stay in place without.
Here's a front shot:
And a close-up:
Can you guys think of any potential concerns with my installation? Do I really need to glue, tape or zip-tie them?
There's a small area below the license plate where the foam allows some air, so approximately 90% of the lower grille opening is blocked.